//
// Created by hsj on 2024-1-4.
// ************************
// UDP没有listen、accept
// ************************
//

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#ifdef WIN32
//windows minGW64
//inet_ntop函数：_WIN32_WINNT
#ifdef _WIN32_WINNT
#undef _WIN32_WINNT
#endif
#define _WIN32_WINNT 0x0600
#include <winsock2.h>
#include <ws2tcpip.h>
//#pragma comment(lib,"ws2_32.lib")
#else
//linux  gcc
#include <arpa/inet.h>
#include <sys/socket.h>
#include <netinet/in.h>
#endif


#define BUF_SIZE 30
void error_handling( char *message);

int main(int argc, char *argv[] ){
    int serv_sock;
    char message[BUF_SIZE];
    int str_len;
    socklen_t clnt_adr_sz;
    char port[]="7788";

    struct sockaddr_in serv_adr, clnt_adr;
//    if(argc!=2){
//        printf("Usage : %s <port>\n", argv[0]);
//        exit(1);
//    }

    serv_sock=socket(PF_INET, SOCK_DGRAM,0);
    if(serv_sock == -1)
        error_handling( "UDP socket creation error");

    memset(&serv_adr, 0, sizeof(serv_adr));
    serv_adr.sin_family=AF_INET;
    serv_adr.sin_addr.s_addr=htonl(INADDR_ANY);
    serv_adr.sin_port=htons (atoi(/*argv[1]*/port));

    if(bind(serv_sock, (struct sockaddr* )&serv_adr, sizeof(serv_adr))==-1)
        error_handling("bind() error");
    printf("[udp] service listen on port: %s\n",port);

    while(1){//死循环
        clnt_adr_sz=sizeof(clnt_adr);
        //接受UDP数据
        str_len=recvfrom(serv_sock, message, BUF_SIZE, 0,(struct sockaddr*)&clnt_adr, &clnt_adr_sz);

        //获取client端的IP和端口
        //xxx.xxx.xxx.xxx = 15位
        char strClientIP[16];
        memset(strClientIP, 0, sizeof(strClientIP));
        printf("client-->IP:[%s],PORT:[%d]\n", inet_ntop(AF_INET, &clnt_adr.sin_addr.s_addr, strClientIP, sizeof(strClientIP)), ntohs(clnt_adr.sin_port));

        //发送UDP数据
        sendto(serv_sock, message, str_len, 0,(struct sockaddr*)&clnt_adr, clnt_adr_sz);
    }

    close(serv_sock);
    return EXIT_SUCCESS;
}

void error_handling( char *message){
    fputs (message, stderr);
    fputc('\n', stderr);
    exit(1);
}
